When making a bug report, it’s best to provide either a link to the page, or server errors from your logs, or follow the steps in our bug report forum so that we are able to investigate your errors.
Please link me to a custom product you’ve set up on your website so I can investiage.
Without any information, it’s very hard to guess what’s going on.
I would recommend trying the following:
1) Go into your WP Admin > MyStyle Settings > Check the box for disable Flash / HTML5 Only and try again. This should resolve issues with SSL if you’re using https://
2) disable other plugins that might cause conflicts
3) set up a product with product ID 1 for a basic test with a blank square template.